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Simplify promotion move generator

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This patch removes Knight promotion checks from Captures. As a consequence,
it also removes this underpromotion from qsearch.

STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 37776 W: 3113 L: 3023 D: 31640
Ptnml(0-2): 103, 2419, 13755, 2507, 104
https://tests.stockfishchess.org/tests/view/60be6a06457376eb8bcaa775

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 39760 W: 1257 L: 1203 D: 37300
Ptnml(0-2): 11, 1079, 17646, 1133, 11
https://tests.stockfishchess.org/tests/view/60beb972457376eb8bcaa7c5

closes https://github.com/official-stockfish/Stockfish/pull/3536

Bench: 5530620
This commit is contained in:
bmc4 2021-06-07 15:47:37 -03:00 • committed by Stéphane Nicolet
parent 999e142c54
commit 785b708097
2 changed files with 11 additions and 15 deletions
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24
src/movegen.cpp
View file

@ -26,21 +26,16 @@ namespace Stockfish {
namespace {
template<GenType Type, Direction D>
ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {
ExtMove* make_promotions(ExtMove* moveList, Square to) {
if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
{
*moveList++ = make<PROMOTION>(to - D, to, QUEEN);
if (attacks_bb<KNIGHT>(to) & ksq)
*moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
}
if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
{
*moveList++ = make<PROMOTION>(to - D, to, ROOK);
*moveList++ = make<PROMOTION>(to - D, to, BISHOP);
if (!(attacks_bb<KNIGHT>(to) & ksq))
*moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
*moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
}
return moveList;
@ -57,7 +52,6 @@ namespace {
constexpr Direction UpRight = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
constexpr Direction UpLeft = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
const Square ksq = pos.square<KING>(Them);
const Bitboard emptySquares = Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces();
const Bitboard enemies = Type == EVASIONS ? pos.checkers()
: Type == CAPTURES ? target : pos.pieces(Them);
@ -82,6 +76,7 @@ namespace {
// To make a quiet check, you either make a direct check by pushing a pawn
// or push a blocker pawn that is not on the same file as the enemy king.
// Discovered check promotion has been already generated amongst the captures.
Square ksq = pos.square<KING>(Them);
Bitboard dcCandidatePawns = pos.blockers_for_king(Them) & ~file_bb(ksq);
b1 &= pawn_attacks_bb(Them, ksq) | shift< Up>(dcCandidatePawns);
b2 &= pawn_attacks_bb(Them, ksq) | shift<Up+Up>(dcCandidatePawns);
@ -111,13 +106,13 @@ namespace {
b3 &= target;
while (b1)
moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(b1), ksq);
moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(b1));
while (b2)
moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(b2), ksq);
moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(b2));
while (b3)
moveList = make_promotions<Type, Up >(moveList, pop_lsb(b3), ksq);
moveList = make_promotions<Type, Up >(moveList, pop_lsb(b3));
}
// Standard and en passant captures
@ -206,6 +201,7 @@ namespace {
moveList = generate_moves<Us, ROOK, Checks>(pos, moveList, target);
moveList = generate_moves<Us, QUEEN, Checks>(pos, moveList, target);
}
if (!Checks || pos.blockers_for_king(~Us) & ksq)
{
Bitboard b = attacks_bb<KING>(ksq) & (Type == EVASIONS ? ~pos.pieces(Us) : target);
@ -227,10 +223,10 @@ namespace {
} // namespace
/// <CAPTURES> Generates all pseudo-legal captures plus queen and checking knight promotions
/// <QUIETS> Generates all pseudo-legal non-captures and underpromotions (except checking knight)
/// <CAPTURES> Generates all pseudo-legal captures plus queen promotions
/// <QUIETS> Generates all pseudo-legal non-captures and underpromotions
/// <EVASIONS> Generates all pseudo-legal check evasions when the side to move is in check
/// <QUIET_CHECKS> Generates all pseudo-legal non-captures giving check, except castling
/// <QUIET_CHECKS> Generates all pseudo-legal non-captures giving check, except castling and promotions
/// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
///
/// Returns a pointer to the end of the move list.

2
src/search.cpp
View file

@ -1464,7 +1464,7 @@ moves_loop: // When in check, search starts from here
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
// queen and checking knight promotions, and other checks(only if depth >= DEPTH_QS_CHECKS)
// queen promotions, and other checks (only if depth >= DEPTH_QS_CHECKS)
// will be generated.
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->captureHistory,